Monday, June 21, 2010

Treatment of AKI

The management of AKI hinges on identification and treatment of the underlying cause. In addition to treatment of the underlying disorder, management of AKI routinely includes the avoidance of substances that are toxic to the kidneys, called nephrotoxins. These include NSAIDs such as ibuprofen, iodinated contrasts such as those used for CT scans, and others.

Monitoring of renal function, by serial serum creatinine measurements and monitoring of urine output, is routinely performed. In the hospital, insertion of a urinary catheter helps monitor urine output and relieves possible bladder outlet obstruction, such as with an enlarged prostate.

Specific therapies
In prerenal AKI without fluid overload, administration of intravenous fluids is typically the first step to improve renal function. Volume status may be monitored with the use of a central venous catheter to avoid over- or under-replacement of fluid.

Should low blood pressure prove a persistent problem in the fluid-replete patient, inotropes such as norepinephrine and dobutamine may be given to improve cardiac output and hence renal perfusion. While a useful pressor, there is no evidence to suggest that dopamine is of any specific benefit, and may be harmful.

The myriad causes of intrinsic AKI require specific therapies. For example, intrinsic AKI due to Wegener's granulomatosis may respond to steroid medication. Toxin-induced prerenal AKI often responds to discontinuation of the offending agent, such as aminoglycoside, penicillin, NSAIDs, or acetaminophen.

If the cause is obstruction of the urinary tract, relief of the obstruction (with a nephrostomy or urinary catheter) may be necessary.

Diuretic agents
The use of diuretics such as furosemide, while widespread and sometimes convenient in ameliorating fluid overload, does not reduce the risk of complications or death. In practice, diuretics may simply mask things, making it more difficult to judge the adequacy of resuscitation.

Renal replacement therapy
Renal replacement therapy, such as with hemodialysis, may be instituted in some cases of AKI. A systematic review of the literature in 2008 demonstrated no difference in outcomes between the use of intermittent hemodialysis and continuous venovenous hemofiltration (CVVH). Among critically ill patients, intensive renal replacement therapy with CVVH does not appear to improve outcomes compared to less intensive intermittent hemodialysis.

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